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Characterization of a CMOS 135-GHz Low Noise Amplifier with Two Different Noise Measurement Methods
Doyoon Kim,Sooyeon Kim,Kiryong Song,Jungsoo Kim,Junghwan Yoo,Jae-Sung Rieh 대한전자공학회 2018 Journal of semiconductor technology and science Vol.18 No.4
A D-band low-noise amplifier (LNA) has been developed based on a 65-nm CMOS technology, which showed a measured peak gain of 16.1 dB at 134.5 GHz. The noise property of the fabricated amplifier was characterized with two different noise measurement techniques: the cryogenic Y-factor method and the N-times power method. The two methods showed a minimum value of the noise figure of 10.7 dB and 14.7 dB, respectively.
Donghyun Lee,Seungchan Cho,Junghwan Kim,Sang-bok Lee,Sang-kwan Lee 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.2
B4C/Al composite is mainly used for neutron absorbing materials, which is one of the components of equipment that manages spent nuclear fuel. There are various processes for manufacturing neutron absorbing materials, but most of them are based on the powder metallurgy. In this study, B4C/Al composite in which the reinforcement was uniformly dispersed was manufactured by using the stir casting process. The microstructure, thermal neutron absorption rate, mechanical properties and dispersibility of the reinforcement of the prepared B4C/Al composite were analyzed.
Donghyun Lee,Seungchan Cho,Junghwan Kim,Sang-Bok Lee 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.1
In this study, for thermal neutron absorption, an aluminum metal composite in which B4C particles were uniformly dispersed was prepared using stirring casting and hot rolling processes. The microstructure, thermal neutron absorption rate, mechanical properties and dispersibility of the reinforcement of the prepared B4C/Al composite were analyzed. The composite in which the 40 μm sized B4C particles were uniformly dispersed increased the tensile strength as the volume ratio of the reinforcement increased.
Surface Characterization of ε-particle, Trivalent- and Tetravalent-metal Doped Uranium Dioxide
Jeongmook Lee,Dong Woo Lee,Junghwan Park,Tae-Hyeong Kim,Jong-Yun Kim,Sang Ho Lim 한국방사성폐기물학회 2023 한국방사성폐기물학회 학술논문요약집 Vol.21 No.2
This study explores the impact of metal doping on the surface structure of spent nuclear fuels (SNFs), particularly uranium dioxide (UO2). SNFs undergo significant microstructural changes during irradiation, affecting their physical and chemical properties. Certain elements, including actinides and lanthanides, can integrate into the UO2 lattice, leading to non-stoichiometry based on their oxidation state and environmental conditions. These modifications are closely linked to phenomena like corrosion and oxidation of UO2, making it essential to thoroughly characterize SNFs influenced by specific element doping for disposal or interim storage decisions. The research employs X-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy to investigate the surface structure of UO2 samples doped with elements such as Nd3+, Gd3+, Zr4+, Th4+, and ε-particles (Mo, Ru, Pd). To manufacture these samples, UO2 powders are mixed and pelletized with the respective dopant oxide powders. The resulting pellet samples are sintered under specific conditions. The XRD analysis reveals that the lattice parameters of (U,Nd)O2, (U,Gd)O2, (U,Zr)O2, and (U,Th)O2 linearly vary with increasing doping levels, suggesting the formation of solid solutions. SEM images show that the grain size decreases with higher doping levels in (U,Gd)O2, (U,Nd)O2, and (U,Zr)O2, while the change is less pronounced in (U,Th)O2. Raman spectroscopy uncovers that U0.9Gd0.1O2-x and U0.9Nd0.1O2-x exhibit defect structures related to oxygen vacancies, induced by trivalent elements replacing U4+, distorting the UO2 lattice. In contrast, U0.9Zr0.1O2 shows no oxygen vacancy-related defects but features a distinct peak, likely indicating the formation of a ZrO8-type complex within the UO2 lattice. ε-Particle doped uranium dioxide shows minimal deviations in surface properties compared to pure UO2. This structural characterization of metal-doped and ε-particle-doped UO2 enhances our understanding of spent nuclear fuel behavior, with implications for the characterization of radioactive materials. This research provides valuable insights into how specific element doping affects the properties of SNFs, which is crucial for managing and disposing of these materials safely.
Junghwan Do,Yoonsuk Cho,Hoseop Yun,Kyungna Jung 대한화학회 2005 Bulletin of the Korean Chemical Society Vol.26 No.8
Two new copper vanadium borophosphate compounds, (NH4)(C2H10N2)5.5[Cu(C2H8N2)2]3[V2P2BO12]6•17H2O, Cu-VBPO1 and (NH4)(C2H10N2)3.5[Cu(C2H8N2)2]5[V2P2BO12]6•18H2O, Cu-VBPO2 have been hydrothermally synthesized and characterized by single crystal X-ray diffraction, thermogravimetric analysis, IR spectroscopy, and elemental analysis. The structure of Cu-VBPO1 contains a layer anion, {[Cu(C2H8N2)2]3[V2P2BO12]6}12, whereas Cu-VBPO2 has an open framework anion, {[Cu(C2H8N2)2]5[V2P2BO12]6}8. Crystal Data: (NH4)(C2H10N2)5.5[Cu(C2H8N2)2]3[V2P2BO12]6•17H2O, monoclinic, space group I2/m (no. 12), a = 15.809(1) Å, b = 31.107(2) Å, c = 12.9343(8) Å, = 104.325(1)o, Z = 2; (NH4)(C2H10N2)3.5[Cu(C2H8N2)2]5[V2P2BO12]6• 18H2O, tetragonal, space group P42/mnm (no.136), a = 26.832(1) Å, c = 18.021(1) Å, Z = 4.